[web] [WIP] Optimize IO slightly

web/src/main.rs

@@ -3,6 +3,7 @@ pub mod contrast;
 pub mod statics;
 pub mod configuration;
 
+use std::io::IoSlice;
 use crate::statics::StaticAsset;
 use smol::io::AsyncWriteExt;
 use smol::stream::StreamExt;
@@ -151,10 +152,10 @@ async fn handle_request(
 		},
 	};
 
-	if let Err(e) = stream.write_all(
+	if let Err(e) = stream.write_vectored(
 		route_request(&req)
 			.generate_response(settings)
-			.into_bytes()
+			.into_io_slices()
 			.as_ref()
 	).await {
 		log::warn!(
@@ -484,32 +485,32 @@ pub struct Response {
 }
 
 impl Response {
-	fn into_bytes(self) -> Vec<u8> {
+	fn into_io_slices(&self) -> Vec<IoSlice<'_>> {
 		let mut output = Vec::with_capacity(
 			// Is computing the exact length of the output necessary?  No.
 			// Do we gain any even vaguely measurable performance gain by preventing reallocation?  No.
 			// Am I doing it anyway?  Yes.
 			// It is late and I am tired and you are nothing to me you can't tell me what to do
-			14 + // HTTP/1.1 200\r\n
-			self.headers
-				.iter()
-				.map(|(h1, h2)| h1.len() + h2.len() + 4)
-				.sum::<usize>() +
-			2 + // \r\n
-			self.body.len()
+			5 + 4 * self.headers.len()
 		);
 
-		output.extend_from_slice(b"HTTP/1.1 ");
-		output.extend_from_slice(self.status.to_string().as_bytes());
-		output.extend_from_slice(b"\r\n");
+		output.extend_from_slice(&[
+			IoSlice::new(b"HTTP/1.1 "),
+			IoSlice::new(self.status.to_string().as_bytes()),
+			IoSlice::new(b"\r\n"),
+		]);
 		for (h1, h2) in self.headers.iter() {
-			output.extend_from_slice(h1);
-			output.extend_from_slice(b": ");
-			output.extend_from_slice(h2);
-			output.extend_from_slice(b"\r\n");
+			output.extend_from_slice(&[
+				IoSlice::new(h1),
+				IoSlice::new(b": "),
+				IoSlice::new(h2),
+				IoSlice::new(b"\r\n"),
+			]);
 		}
-		output.extend_from_slice(b"\r\n");
-		output.extend_from_slice(&*self.body);
+		output.extend_from_slice(&[
+			IoSlice::new(b"\r\n"),
+			IoSlice::new(&*self.body),
+		]);
 		return output;
 	}
 }